In recent years, from the viewpoint of reduction of equipment maintenance costs and reduction of environmental load, weather resistance improvement of polymer material used under severe condition such as outdoors is strongly required.
For the purpose of weather resistance improvement of the polymer material used as coating, patent document 1 proposes adding a hindered amine light stabilizer having a piperidine skeleton (hereinafter, referred to as “HALS”), particularly whose nitrogen atom is substituted by various kinds of OR groups (hereinafter, referred to as “NOR-HALS”) (O represents oxygen atom, R represents alkyl group) to coating material components.
Although the NOR-HALS has an advantageous effect in weather resistance improvement of the polymer material, it has a problem of gradually vanishing from the polymer material by migration or volatilization and the advantageous effect decreases with time.
For the purpose of solving this problem, patent document 2 proposes copolymerizing a polymerizable NOR-HALS (hereinafter, referred to as “polymerizable NOR-HALS”) having a vinyl group in its molecule, to add to coating material components.